Coaxial multi-stage rotory compressor



Nov. 17, 1970 R. s. ALCOLEA 3,540,315

COAXIAL MUL'II-STAGE ROTARY COMPRESSOR Filed Dec. 5, 1968 4 Sheets-Sheet1 III/l .II/

III I/III III Nov. 17, 1970 R. G. ALCOLEA COAXIAL MULTI-STAGE ROTARYCOMPRESSOR 4 Sheets-Sneex 2 Filed Dec. 3, 1968 Caz-s Nov. 17, 1970 R. G.ALCOLEA 3,540,315

COAXIAL MULTI-STAGE ROTARY COMPRESSOR I Fiied Dec. 3, 1968 4 Sheets-5mms Nov. 17, 1970 R. e. ALCOLEA COAXIAL MULTI-SIAGE ROTARY COMPRESSOR 4Sheets-Shem Filed Dec. 5. 1968 FIG-5 FIG-6 United States Patent3,540,816 COAXIAL MULTI-STAGE ROTORY COMPRESSOR Rafael Gil Alcolea,Ximenez de Quesada 17-3", Cordoba, Spain Filed Dec. 3, 1968, Ser. No.780,809 Claims priority, application Spain, Dec. 5, 1967,

Int. Cl. F041) 13/02 19/02; F04c 1/00 US. Cl. 418-177 16 Claims ABSTRACTOF THE DISCLOSURE A coaxial multi-stage rotary compressor comprising acylindrical rotor which in turn carries and guides generally axiallydisposed and spaced reciprocatable blades of constant length, each endof each blade being also guided in reciprocating movement betweensubstantially elliptical surfaces, the blades always remaining in aradial position with respect to said rotor and, therefore, perpendicularto the tangent to the surface of the rotor which is adapted to drivesaid blades, one stage of said compressor being between an inner side ofsaid rotor and one elliptical surface and another stage of saidcompressor being between the exterior of said rotor and a secondconcoidal transformated surface.

This invention relates to a multi-stage compressor and more particularlyto a coaxial multi-stage compressor of the rotary type.

Internal combustion engines and thermal engines, in general, includemeans for compressing, or a compression cycle so that the air supportingcombustion with or without fuel incorporated is compressed beforeignition. In such engines the compression takes .place either in thesame chamber where combustion occurs or it is compressed outside of thecombustion chamber by an independent compressor normally called asupercharger. Internal combustion engines of the character describedinclude those which utilize the Otto cycle or are sometimes called fourcycle. Other examples include diesel engines of the type used invehicles or ships. Still other examples include the gas turbines used inairplanes and also in ships.

Compressors used for supercharging are generally not of thereciprocating type because of the high rotational speeds at which theymust operate. Because of these high speeds, problems are involved in theutilization of valves usually associated with reciprocating piston typecompressors. The compressors which have been used for supercharging areof the rotary volumetric or centrifugal type and the power for drivingsuch superchargers is always supplied by the engine itself in the caseof aircraft and surface vehicles. In the case of stationary engines orship engines, the superchargers may be driven by an auxiliary engine.

In the superchargers of the prior art the compression takes place eitherin a single stage or in a multi-stage arrangement wherein the compressorshaft is extended so that the stages of the compressor are extended fromeach other in an axial direction.

In accordance with the instant invention the coaxial arrangement of themultiplicity of stages is such that one stage is about the other and sothe shaft of the compressor is not extended. Further, in accordance withthe instant invention the arrangement is such that inter-cooling maytake place between stages.

Other objects and the nature and advantages of the instant inventionwill be apparent from the following description taken in conjunctionwith the accompanying drawings, wherein:

3,540,816 Patented Nov. 17, 1970 FIG. 1 is a schematic illustration ofthe mathematical principles of a part of the mechanism of the invention;

FIG. 2 is a fragmentary vertical section taken through a portion of theapparatus illustrated in FIG. 3 with arrows showing how air or othermedium to be compressed can be brought into the first stage;

FIG. 3 is a vertical section through the coaxial multistage rotarycompressor taken at right angles to the axis of the rotor;

FIG. 4 is a vertical section taken at right angles to the sectionillustrated in FIG. 3 and also including a receiver below the mechanismwhich is not illustrated in FIG. 3;

FIG. 5 is a fragmentary view partially in perspective and partially insection showing the sealing engagement of a blade with the rotor andalso a cooling passage within the blade; and

FIG. 6 is a detail of the end of a blade after removal of the seal atthe end of a blade.

The coaxial relatively short shaft multi-stage compressor, in accordancewith the invention, consists essentially of three principal parts whichmay be viewed in FIG. 3. These principal parts are as follows:

(A) The first principal part is an interior stationary body 4 having agenerally elliptical interior surface;

(B) An exterior stationary body 3 having a concoidal transformatedinterior surface; and

(C) The third principal part is the rotor 5 which carries and guidesspaced radially disposed sliding blades.

The stationary interior body 4 has its external substantially ellipticalsurface perfectly machined so that the interior ends of the drivenblades can slide thereon with minimum frictional losses andsusbtantially without leakage.

The stationary exterior body 3 is also machined to have a substantiallyelliptical surface which is derived from the external ellipse of theinterior body 4 by adding a constant length to the vector radii drawnfrom the center of that ellipse (i.e. the concoidal transformation ofthe external curve). The functions which are defined in coordinatedpolars in the following formulae, are easily representable, derivableand continuous and can, therefore, be industrially mechanized by anymodern manufacturing proecss (see FIG. 1).

1 cos 0 sin 0 Internal ellipse:

With the above geometrical formulae which bind the various parameters,representing the semi-axis of the ellipses and the thickness of theguide rotor, in the function of the constructively interestingproportions to which the semi-axis and the thickness should correspondto obtain certain compression relations, both for the first phase aswell as for the second phase after due intermediate refrigeration,various axial-biphase compressors can be manufactured for the mostvaried work conditions and requirements of the engines to which they canbe applied.

Further, there can also be included another biphase compressor setlocated at inner part of the interior body that reproduces identicallythe multi-stage compression processes being fed by air compressed fromthe different receivers, thus providing enough upper-pressured air forfluid control.

The simplification of the fluid compression process, together with theopportunity for the practical realization of an intermediaterefrigeration, without the run of the compressed fluid in the firstphase having to overcome a certain length in function with theadmissible losses or the degree of refrigeration required, allow forsome very important economies in the fluid compression operation, whichcan be listed as follows:

(a) Economy of space, as it is an extremely compact unit, depending onits relative dimensions.

(b) Economy and regularity in functioning, as it allows the twoair-pressured receivers of the air partially compressed in each phase tobe contained in a block.

(c) Flexibility of consumption and application with regard to thevarious uses, as direct outlets can be taken from each one of thephases, complying, at the same time, with different pressure demands.

(d) Economies derived from the yield increase through the elimination ofintermediate losses when transferring the compressed air from one phaseto another.

(e) Great increase in the beneficial use of the energy available in theengine through the intermediate refrigeration obtained during thefunctioning of the compressor between one phase and another, to thebenefit of the output of the second phase.

(f) Obtention of high pressures without need of heavy devices, as theresulting differential pressures between its elements partly compensatethe resistance demand of the walls and the final compression turns outto be an approximate product of the compression relations of the twosuperposed phases.

In addition to the aforementioned advantages, there will be otherspresent in the utilization of the invention which will be apparent tothose skilled in the art working with the instant invention.

The operation of the coaxial multi-stage compressor will be betterunderstood when reference is made to the drawings as follows:

The two concentric surfaces of the stationary outer and inner bodies 3,4, determine a continuous cylindrical chamber and delimit a segment ofconstant length for all the vector radii drawn from the center of thecompressor. The cylindrical rotor is of circular section and isconcentric with the said elliptical surface, and revolves within theaforementioned elliptical chamber.

The rotor 5 which has internal and external surfaces revolves withrespect to the two stationary bodies 3, 4, so that the internal walls ofthe rotor 5 are at a constant tangent to the major axis of thestationary body 4 and the external walls of the rotor 5 are at aconstant tangent with the internal surface of the stationary body 3through its minor axis.

In accordance with the instant invention, the blades are always directedtowards the common center of all the surfaces, in whatever position theyare in, they will always be extending in a radial direction and slidebetween parallel surfaces of the exterior of the stationary body 4 andthe interior of the stationary body 3. The blades 10 are each of thesame length.

Between each two consecutive blades it will be noted that as the spacebetween the rotor 5 and the body 4 increases, then the space between therotor 5 and the body 3 decreases.

It is to be understood that the blades may be provided with leakagepreventing devices or sealing devices such as may be necessary to avoidfluid losses between each two consecutive spaces separated by the blades10 and also defined by the interior surfaces of the stationary body 3and the exterior surfaces of the stationary body 4. See FIG. 5, forexample.

The compressed air passing from the space between the rotor 5 and theinterior surface of the stationary body 3 may be led through a coolingmeans or refrigerator which may include a water cooled surface or a finsurface and then the compressed air which has already been cooled may bepassed through a passage from which it enters the space between thestationary body 4 and the interior surface of the rotor 5 whereupon theair is once more compressed in a second stage. schematically theillustration in FIG. 3 would show a multi-stage compression in the orderof about 1 to 15.

As described above, it is contemplated that the partially compressed airfrom the first stage will be passed into the space between thestationary body 4 and the interior space of the rotor 5 through acylindrical passageway in the hollow shaft of the rotor 5. Anotherembodiment illustrated in FIG. 4, which does not include this hollowshaft, does, however, include a block which is traversed by the conduitsthrough which is passed the partially compressed air of the first stageand also cooling water chamber 1.

In FIG. 4, the rotor 5 is illustrated as being associated with a supportbearing 7 and the rotor 5 is adapted to be driven through meshing gearsby the pinion 9 mounted on the driving shaft 8.

In both of the described forms pressurized cooling oil is circulatedacross the contact surface of the block which is formed by inner andouter walls of the rotor 5. This oil fills the chambers disposed in theperiphery of the rotor and serves to lubricate the sides of the blades10 through suitable ports as the blades 10 are carried and guided by therotor 5.

The blades 10, which are constantly guided in their different positionsin relation to the rotor 5, may have friction reducing devices at theirends such as may be afforded by a simple circular elastic surface[O-ring] or tiltable articulated means constantly adaptable to thedifferent slopes of the surface engaged by the end of a blade. The endsof the blades may also be fitted out with housings including draw bandsand double pressure arrangements and such arrangements may be situatedad bee in extensions in the blade ends. To take up lateral thrust,similarly other devices of suitable material may be provided for thepurpose of supporting and guiding in bearing relation the rotor withrespect to the stationary bodies both on the inside and outside.

The interior cooling of the blades 10, apart from the cooled airreceived immediately with the first admission of air to be compressedand some of the cooling communicated thereto after the first compressionstage, is effected, as will be understood by reference to FIG. 5, bypassing a liquid or material similar to that used in the hollow parts ofinlet and outlet valves in internal combustion engines, through hollowportions of the blades 10.

The regulation of pressures in both receivers 6 and 11 is governed,within the relative values related to a given compressor in accordancewith the instant invention, by inlet and outlet valves, guided by gaugedsprings, which permit the upward and downward movement of pressures inthe receivers to be maintained within predetermined tolerances accordingto special requirements of the surface to which the compressors inaccordance with the instant invention are to be put.

When the compressors in accordance with the instant invention areutilized for the purpose of supercharging an explosion or internalcombustion engine, in some circumstances it may be desirable that thetemperature of the compressed air in the second stage he raised beforethe supercharged air is passed to the combustion or explosion engine.This raising of the compressed air temperature may easily be effected byan arrangement wherein the outlet pipe of the receiver on its way to theengine inlet is first passed through a section of the engine exhaustgas, whereby the final pressure can be appreciably increased asrequired. In such circumstances the supercharger may be used inassociation with the engines of the diesel type, semi-diesel type, orsimple Otto cycle engines. or gas turbines. This flexibility in the useof compressors in accordance with the instant invention is extensive andsignificant.

It will be obvious to those skilled in the art that various changes maybe made without departing from the scope of the invention and theinvention is not to be considered limited to what is shown in thedrawings and described in the specification.

I claim:

1. A coaxial multi-stage rotary compressor comprising a cylindricalrotor which carries and guides generally axially disposed and spacedreciprocatable blades of constant length, a first stage chamber definedby the inner surface of an outer substantially elliptical stator and theouter surface of said rotor, a second stage chamber defined by the innersurface of said rotor and the outer surface of a substantiallyelliptical inner stator located within said rotor, each end of eachblade being guided in reciprocating movement between said substantiallyelliptical surfaces which have a common center with the center of saidcylindrical rotor, each blade being guided by guiding means on saidrotor and said elliptical surfaces so that each blade is always radiallydisposed and perpendicular to tangents to surfaces of the rotor which isadapted to drive said blades, said rotor being kept at a constanttangent with an interior surface of said outer stator and the innersurface of said rotor being kept at a substantially constant tangentwith a surface of said inner stator, the blades which are guided by saidrotor are delimited in their reciprocatable movement by an inner surfaceof the outer stator and an outer surface of the inner stator, one stageof said compressor being on the inside of said rotor and another stageof said compressor being on the outside of said rotor, the space betweenconsecutive blades being separated into two compartments in one of whichthe medium to be compressed is subjected to a decreasing volume and inthe other of which the medium is being taken in whereby in an identicalradial section the medium may be taken into the inside of the rotor andbe compressed on the outside of the rotor and whereby the medium whichhas received its first compression on the outside of the rotor may becompressed in a second stage on the inside of the rotor.

2. A coaxial multi-stage rotary compressor in accordance with claim 1,in which the medium from the first compression stage is cooled orrefrigerated before it is passed to the second stage.

3. A coaxial multi-stage rotary compressor in accordance with claim 1,in which medium from the second stage is passed to a cooling means andthe cooled second stage medium is pressure regulated.

4. A coaxial multi-stage rotary compressor comprising a cylindricalrotor which carries and guides generally axially disposed and spacedreciprocatable blades of constant length, a first stage chamber definedby the inner surface of an outer substantially elliptical stator and theouter surface of said rotor, a second stage chamber defined by the innersurface of said rotor and the outer surface of a substantiallyelliptical inner stator located within said rotor, each end of eachblade being guided in reciprocating movement between said substantiallyelliptical surfaces which have a common center with the center of saidcylindrical rotor, each blade being guided by guiding means on saidrotor and said elliptical surfaces so that each blade is always radiallydisposed and perpendicular to tangent to surfaces of the rotor which isadapted to drive said blades, said rotor being kept at a constanttangent with an interior surface of said outer stator and the innersurface of said rotor being kept at a substantially constant tangentwith a surface of said inner stator, the blades which are guided by saidrotor are delimited in their reciprocatable movement by an inner surfaceof the outer statorand an outer surface of the inner stator, one stageof said compressor being on the inside of said rotor and another stageof said compressor being on the outside of said rotor, wherein saidrotor comprises an inner wall spaced from an outer wall between which isa passage for oil circulation which effects the dual purpose of coolingthe spaces immediately adjacent the walls of said rotor and also effectslubrication of the sides of the blades which slides through the rotorwalls.

5. A coaxial multi-stage rotary compressor comprising a cylindricalrotor which carries and guides generally axially disposed and spacedreciprocatable blades of constant length, a first stage chamber definedby the inner surface of an outer substantially elliptical stator and theouter surface of said rotor, a second stage chamber defined by the innersurface of said rotor and the outer surface of a substantiallyelliptical inner stator located within said rotor, each end of eachblade being guided in reciprocating movement between said substantiallyelliptical surfaces which have a common center with the center of saidcylindrical rotor, each blade being guided by guiding means on saidrotor and said elliptical surfaces so that each blade is always radiallydisposed and perpendicular to tangents to surfaces of the rotor which isadapted to drive said blades, said rotor being kept at a constanttangent with an interior surface of said outer stator and the innersurface of said rotor being kept at at a substantially constant tangentwith a surface of said inner stator, the blades which are guided by saidrotor are delimited in their reciprocatable movement by an inner surfaceof the outer stator and an outer surface of the inner stator, one stageof said compressor being on the inside of said rotor and another stageof said compressor being on the outside of said rotor, the blades beingprovided with hollow longitudinal and transverse extensions throughwhich a cooling liquid circulates under the influence of the motionimparted by the rotor and the substantially elliptical surfaces whichlimit the reciprocation of the blades.

6. A coaxial multi-stage rotary compressor comprising a cylindricalrotor which carries and guides generally axially disposed and spacedreciprocatable blades of constant length, a first stage chamber definedby the inner surface of an outer substantially elliptical stator and theouter surface of said rotor, a second stage chamber defined by the innersurface of said rotor and the outer surface of a substantiallyelliptical inner stator located within said rotor, each end of eachblade being guided in reciprocating movement between said substantiallyelliptical surfaces which have a common center with the center of saidcylindrical rotor, each blade being guided by guiding means on saidrotor and said elliptical surfaces so that each blade is always radiallydisposed and perpendicular to tangents to surfaces of the rotor which isadapted to drive said blades, said rotor being kept at a constanttangent with an interior surface of said outer stator and the innersurface of said rotor being kept at a substantially. constant tangentwith a surface of said inner stator, the blades which are guided by saidrotor are delimited in their reciprocatable movement by an inner surfaceof the outer stator and an outer surface of the inner stator, one stageof said compressor being on the inside of said rotor and another stageof said compressor being on the outside of said rotor, the firstsubstantially elliptical surface being formed on an inner stator whichhas provided therein a hollow chamber in the central axial area adjacentthe axis of said rotor which hollow chamber houses both the rotorbearings and the feed passages for medium compressed in a stage of thecoaxial multi-stage rotary compressor.

7. A coaxial multi-stage rotary compressor including a cylindrical rotorcarrying and guiding generally axially arranged spaced blades ofconstant length, said blades being arranged for reciprocatable movementbetween substantially spaced exterior and interior elliptical stationaryconcentric surfaces so that the blades are always radially disposed withrespect to the geometric center of said elliptical concentric surfaces,said compressor being characterized in that the cylindrical rotor isconstantly in contact, at a portion of its inner surface, with surfaceportions at the ends of the major axis of the interior ellipticalsurface, said rotor being constantly in contact, at a portion of itsexternal surface with surface portions at the ends of the minor axis ofthe exterior elliptical surface, whereby there is created within therotor a first independent chamber and there is created on the outside ofsaid cylindrical rotor a second independent chamber.

8. A coaxial multi-stage rotary compressor according to claim 7,characterized in that the space between consecutive blades is dividedinto two compartments by a portion of the cylindrical rotor which has anouter surface and an inner surface.

9. A coaxial multi-stage rotary compressor according to claim 7,characterized in that the space between consecutive blades is delimitedby surface portions of said elliptical surfaces and a portion of thecylindrical surfaces of said rotor and by the surfaces of the blades,whereby there is created twice as many compartments as the number ofblades.

10. A coaxial multi-stage rotary compressor according to claim 7,characterized in that a radial space between two consecutive bladesforms an exterior compartment and an interior compartment and wherebythe medium to be compressed may be introduced into the exteriorcompartment and additionally compressed in the interior compartment.

11. A coaxial multi-stage rotary compressor according to claim 10,characterized in that the medium to be compressed from the firstcompression compartment is passed to a cooling means and subsequentlypassed to the second compression compartment.

12. A coaxial multi-stage rotary compressor according to claim 10,characterized in that the medium to be compressed from the secondcompression compartment is passed to a cooling means and then ispressure regulated.

13. A coaxial multi-stage rotary compressor according to claim 7,characterized in that the space between the inner surface and the outersurface of said rotor provides a passage for circulating and lubricatingoil for effecting cooling of said compartments and lubrication of thesides of the blades which slide through the rotor walls.

14. A coaxial multi-stage rotary compressor according to claim 7,characterized in that the blades are hollow so that cooling liquid maybe circulated through said hollow blades.

15. A coaxial multi-stage rotary compressor according to claim 7,characterized in that the interior elliptical stationary surface hashollow portions therein wherein are located the rotor bearings and thefeed passages for the medium to be compressed including the passagesbetween the first and second compartments.

16. A coaxial multi-stage rotary compressor according to claim 7,characterized in that the interior elliptical element comprisespassageways for medium to be com pressed and cooling chambers foreffecting inter-cooling.

References Cited UNITED STATES PATENTS 1,666,466 4/1928 Peters 103-1362,280,272 4/1942 Sullivan 103-136 X 2,371,942 3/1945 Armstrong 103-1362,521,592 9/1950 McManus 230-158 2,827,857 3/ 1958 Eserkaln.

CARLTON R. CROYLE, Primary Examiner W. J. KRAUSS, Assistant Examiner

